"So now I certainly reach a point, where I have to answer certain questions to myself: 'What goals do I have that I did not reach yet? Do I want to prove myself always at the same club and always under the same circumstances?'"

He added: "This is a question of personal challenges. It is not about classical career questions, but about questions for your life.

"Those are the questions that drive you on as a human being."

Boateng has only spent one season outside of Germany in his career – the 2010-11 campaign at Manchester City.

He has been linked with a return to City, as well as their rivals Manchester United.